Workshop tales, trials and disasters.
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21 posts • Page 1 of 1
OK, I've made some very basic errors, so i need to ask some pretty basic questions...
I am not a great climber (think worse than Andy Schleck on TT bike) so thought a compact crankset (34/50) and new cassette (12-28) would help get me up some big hills. Currently running a 9 speed Shimano Tiagra groupset with 39/53 and 12-21.Did a lot of research to find a compact crank (FC-4550) compatible with my 9 speed chain and sourced it from PBK. The Shimano site and this driver train chart were quite useful.
Finally got around to fitting the new cranks. Got the cranks off OK. Discovered I had an Octalink V2 BB,
whilst my brand new cranks are Hollowtech II
Options included sell the new cranks and get a new set that fits the current BB. Better option may be to replace BB-something I have never attempted before (bit new at being a bike mechanic, this was actually the first time I've had the cranks off!). Can really recommend the X-Tools toolkit from CRC-has everything i need and great price!
Worked out I had a 68mm BB with British threads so could work out which way to loosen the BB. Got the BB out okay to confirm 68-113 BB.
My Question is: Can I take the current BB out and fit a Hollowtech BB of the correct dimensions? Are the holes the BB goes into a standard size/will Hollowtech II fit?
Looks like the 6700 BB should work?
But, having made one mistake i want to avoid another.
Whilst I had the BB out, I noticed it was a bit rusty and even worse when I looked inside:
It all cleaned up OK and I used lots of grease putting it back together. Shouldn't there be a drain hole?
All advice much appreciated
Merida 903 from the LBS; Diesel engine
What was your mistake? The Hollowtech crankset has an integrated axle and includes external bearings. This replaces the existing BB.
Since you now have the old BB out, it will take about 5 minutes more screw in the bearings, insert the axle and attach the crankarm to the other side.
Assuming the OP indeed bought the bearing cups at the same time as the cranks, they dont come as a kit. Now comes the interminable wait as you order the 6700 and it gets shipped.
MY RIDES: My Velospace Profile
Probably a good idea to get the BB shell (the part of the frame that the bottom bracket screws into) faced before putting the HT2 BB in. Easy and quick for a LBS to do ~$10-20 IME, but the tool is very expensive so not worth doing yourself. Once it is done it is done for the life of the frame.
The last Hollowtech crankset I fitted did indeed come as a kit. It was an LX T661 and included the right crank arm with spindle, chainrings and axle, the left crank arm and cap, the external bearing in their cups, and a set of three spacers for chain line adjustment.
The Shimano road bike cranksets don't come with the BB bearing cups but the mountain bike cranksets do.
Well, according to the Shimano technical docs, the FC-4550 seems to.
Only diference I can see from the T661 LX crankset I last fitted is that it does not use the same arrangement of spacers.
Bought two sets of shimano hollowtech 2 road cranksets, 5600 105 and 7800 dura ace. Neither came with the bearing cups.
You will need one of these or similar to install the bearing cups.
It is good system IMO. Very easy to swap cranks and renew the bearing cups which are cheap
Looks like you have an alloy frame, in which case the rusty gunk is related to your old BB, not the frame. Clean it all out (a soft wire brush will do nicely), and make sure you grease liberally all threads before you install the new BB.
A drain hole would be a good idea, but you'll probably have drain holes near the rear dropouts Ion the inside) - so after a wet ride, stand the bike up on its rear wheel so the water can drain out of these holes.
thanks for the feedback. Jim was on the money when he suggested the BB didn't come with the cranks (although the box with all the tick options for contents suggests it might be an option).
Thanks Ronk, i think you answered my very basic question, I wasn't sure if the new Hollowtech BB would screw right into the hole left by the old Octalink BB (presuming i get correct dimension 68-113). Do the 1.37"x 24T dimensions describe the size and thread of the hole?
Thanks Velo13, the gunky rusty stuff was from BB. The frame cleaned up well with a rag and toothbrush:
I'm learning...if I do decide to drill a drain hole, I will do it whilst I have the BB out!
many thanks and cheers.
Merida 903 from the LBS; Diesel engine
You have a standard 68mm english bb shell, so don't need to worry about the dimensions, the FC-4550 fits 68mm and 70mm shells.
Just order the correct bb according to the drivetrain compatibility chart you posted. The BB is really only the bearings in their cups, since the axle is attached to the right crank arm. As has been posted, you will need to buy a wrench for the bearing cups - you can get one that includes the cap tool for around $30.
Screw the cups in and tighten them, then insert the axle, fit the left crankarm and screw in the cap finger-tight with the tool and torque the bolts, making sure the stopper plate is pushed fully home first. Refer to the installation instructions here.
That it, it's simplest crankset I've ever fitted.
If you are going external bearings, it is a good idea to get the BB shell ends faced at your LBS. If not, at least scrape or sand the paint off the ends of the frame since the bearing cups seat on the ends of the BB shell. You could try installing the cups without doing anything at all, but not recommended by many. I have got BB shells faced and just sanded the paint off. Sanding worked for me.
Is the issue here creaking, if you don't sand the paint off?
By the way I got those sram 900 cranks installed. BBright isn't so bad a system once you find some instruction as to how it works
It may creak, but the real issue is that you need to cups to be as close to perfectly aligned as possible. Getting the BB shell faced is one of the things you can do for this. If the cups are not well aligned then can score the axle which will then not sit properly on the bearings and wear them, and the bearings of any replacement BBs, out more quickly than they should. The only remedy for a scored axle is to replace the crankset. It is more important to check the bearings than with a cartridge BB. On the plus side, replacing the BB is very cheap.
One of the things I like about the Campy power/ultratorque systems is the bearings are pressed on to the axle rather than into the cups so the cups would/should wear more than the axle. Unfortunately that means you need expensive tools - bearing pullers and the like - to work on/replace them. Sigh. There really is no such thing as a free lunch (except the team lunch at work tomorrow ).
I have not bothered about getting the shell faced for any of the cranksets I've fitted, and have not encountered problems with any of them. It's an inconvenience that's not worth the trouble unless an issue actually occurs.
If a problem emerges it is most likely to manifest as premature bearing wear. Replacement bearings are cheap at around $15 for the set in question, so if they wore out prematurely for no other apparent reason, that's when I'd suspect misalignment of the shell and get it faced.
There is an opinion than having the shell faced is not needed. I too belong to this group for quality made frames.
I have had what I thought was a creaking bb. Turned out to be other cause after much frustration. I might take Nobody's advice and remove the paint with some emery paper next time the shells are out. I can see how a lump of paint in one spot could cause alignment issues. Hasn't been a problem to date though.
I think Simonn has covered it. Surly recommend removing the paint with a sharp knife as their frames are already faced.
http://surlybikes.com/info_hole/spew/sp ... teel_frame
I got my Clamont faced at the LBS. I just measured it in various places around the circumference with vernier calipers (as the frame is bare). The variance was ~0.3mm. The Avanti just got a sanding. The Surly CC got the knife paint removal as recommended above. I've never had problems with any of them.
Where did you get the instructions?
Someone on the cervelo forum has fitted them and advised some plastic spacer washers were required, neither of which was mentioned in the instruction sheet that came with the crankset. There were instructions and spacers for bb30 which is 68mm wide, but not bbright which is 79 mm wide and spaced asymetrically in the frame. have ridden it with a 28-11 rear cassette and it is changing well, better than the compact fsa crankset did.
Thanks, I'll scrape or sand the Azzurri next time I have a look at the bb cups
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